This invention relates to laser modulation and reliability particularly for operation in high temperature applications.
The upper operating temperature of optical modules may be limited by the lifetime of the lasers and/or the light emitting diodes (LEDs) used in the modules. For example, the lifetime may be limited by long term wear out. The upper operating temperature of optical modules may be extended by using devices that are capable of operating at high temperatures and using heat sinking. The upper operating temperature of optical modules may also be extended by operating the devices with the minimum possible bias current. For relatively low-speed applications (below 1 Gbps), optical modules may be conceived and implemented with the capability to operate in ambient temperatures as high as 150° C. The lifetimes (mean-time-to-failure or “MTTF”) of such devices may be thousands to ten thousands of hours. These lifetimes may be sufficient for some applications. However, many applications, such as deep-hole oil drilling and jet engine control, require operating temperatures of 175° C. or even higher. Current technology does not provide a way of achieving these temperatures with sufficient optical module lifetime as the laser and/or LED lifetime may be severely degraded due to the inherent physics that cause laser degradation, such as migration of defects. Thermoelectric coolers may be a potential solution; however, these devices also lack the ability to operate reliably at very high temperatures.